Writing in the Bill & Melinda Gates Foundation’s “Impatient Optimists” blog, Bill Gates, co-chair of the foundation, discusses the content of his annual letter, which was published Wednesday. “This year, I concentrate on the power of clear goals and accurate measurement — simple concepts really — to improve the lives of the poorest people around the globe,” he writes, adding, “Not only do clear goals and measures allow governments to spend their aid money more efficiently, it builds the political will to continue funding aid programs by proving how successful they are” (1/29).